It is often desirable to form a seal with an inside wall of an opening or a tube. This may be done to completely block or plug the opening, or tube or to connect an adapter or similar structure to the opening or tube. For example, one method of filling a vehicle radiator requires establishing a partial vacuum in the radiator. This is done by inserting an adapter into the radiator filler neck, forming a seal between the adapter and the inside wall of the filler neck and using a pump to remove air from the radiator through the adapter. An opening in the adapter is then connected to a source of clean radiator fluid, and the pressure difference between the inside of the radiator and ambient pressure forces the clean radiator fluid into the radiator.
Conventional adapters for filling vehicle radiators generally include a flexible seal member that is insertable into the radiator filler neck, a shaft that extends through the flexible seal member, and two bodies at one end of the seal member that are connected to one another by screwthreads. The shaft is connected to one of the bodies, extends through the other body and the seal member and is connected to the seal member. Starting with the two bodies screwed together, the flexible seal member is inserted into the filler neck, and the bodies are then screwed apart from one another. This action moves the top of one body away from the bottom of the other body, pulls the shaft toward the bodies and compresses the seal member. Such compression of the seal member causes the outer wall of the seal member to bulge and press against the inside wall of the tube. As the bodies are unscrewed further, the connection between the sidewall and the seal member becomes tighter, and a fluid-tight seal with the tube sidewall is formed.
Filler necks can vary widely in diameter. A tapered flexible seal member may allow a single adapter to be used in finer necks having a small range of diameters. However, multiple adapters generally must be provided to cover the full range of filler neck diameters that are present on automotive radiators today.
Using different adapters for filler necks having different diameters works adequately, but this requires purchasing and maintaining multiple adapters to cover the entire range of filler neck sizes that is likely to be encountered. It would be desirable to provide a device that forms a seal with the inside of an opening or a tube such as a filler neck that can be used with openings and tubes that have a wide range of diameters and which device can be sealed to and unsealed from the interior of the opening or tube in a simple manner.